1. DOVA-Alanine aminotransferase. Purification of the enzyme from Clostridium will be followed by specificity and mechanistic studies to answer questions relating to the relevance of this enzyme for the biosynthesis of delta-aminolevulinic acid (ALA) and to its irreversibility. 2. Clostridial ALA dehydratase. Two forms of this enzyme have been detected. The proportions of the two forms appear to depend on bacterial growth conditions. This problem will be investigated with the use of certain new inhibitors of the enzyme which still permit growth of the organism. 3. NMN deamidase. Mechanistic studies on the role of the heat-stable component of this enzyme and on the association of this component with the heat-sensitive subunit will be carried out.